Medical Definitions - P

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PaO2 - post-ductal arterial saturation.

Patau syndrome - also known as Trisomy 13; The condition of having three copies of chromosome 13 that results in a syndrome characterized by mental retardation and defects to the central nervous system and heart.

Patent foramen ovale - also known as PFO; a defect in the septum (wall) between the two upper (atrial) chambers of the heart. The defect is an incomplete closure of the atrial septum that results in the creation of a flap or a valve-like opening in the atrial septal wall. A PFO is present in everyone before birth but seals shut in about 80 percent of people. The failure to close is associated with PPHN.

Pavulon - a paralyzing medication.

Pectus excavatum - also known as shrunken or funnel chest; a congential condition where the ribs and sternum do not develop normally resulting in a shrunken in appearance of the chest.

PEEP - positive end-expiratory pressure; a method of ventilation in which airway pressure is maintained above atmospheric pressure at the end of exhalation by means of a mechanical impedance, usually a valve, within the circuit. The purpose of PEEP is to increase the volume of gas remaining in the lungs at the end of expiration in order to decrease the shunting of blood through the lungs and improve gas exchange.

Pericardium - the fibroserous sac enclosing the heart and the roots of the great vessels.

Perinatologist - an obstetrical subspecialist concerned with the care of the mother and fetus at higher-than-normal risk for complications.

Perinephric fluid - fluid surrounding the kidney. The 2 most common causes are abscess and hematoma.

Peritoneal dialysis - form of dialysis that uses the patient's own body tissues inside of the belly (abdominal cavity) to act as a filter.

Persistent fetal circulation (PFC) - persistent pulmonary hypertension in the newborn infant, without demonstrable cardiac disease.

Persistent pulmonary vascular obstruction - see PPHN and/or PFC.

Persistent transitional circulation - see PPHN and/or PFC.

perivascular - near or around a vessel.

ph - a measure of the acidity or alkalinity of a fluid.

Phosphatidylcholine - a phospholipid comprising choline linked to phosphatidic acid; it is a major component of cell membranes and is localized preferentially in the outer surface of the plasma membrane.

Phosphatidylglycerol (PG) - a phosphatidic acid that is a constituent in human amniotic fluid and is used as an indicator of fetal lung maturity when present in the last trimester of gestation.

Phospholipids - the major lipids in cell membranes. Any of various phosphorous-containing lipids that are composed mainly of fatty acids, a phosphate group, and a simple organic molecule.

Phrenic nerve - the nerve that controls the diaphragm.

Pia mater - the innermost of the three meninges covering the brain and spinal cord. The fine vascular membrane that closely envelops the brain and spinal cord under the arachnoid and the dura mater.

PICC line - peripherally inserted central catheter; a form of intravenous access that can be used for a prolonged period of time.

PICU - pediatric intensive care unit; a hospital ward for critically ill children.

Pitocin - brand name of the drug oxytocin; used to induce labor.

Plaister-Killian syndrome - also known as tetrasomy 12p mosaicism or Pallister mosaic aneuploidy syndrome; an extremely rare genetic disorder; occurs due to tetrasomy of the twelfth chromosome. This leads to the development of isochromosome 12p, made up of the two short legs of the chromosome. Because not all cells have the extra isochromosome, it is mosaic.

Platelet - also known as blood platelet or thrombocyte; a minute, irregularly shaped, disklike cytoplasmic body found in blood plasma that promotes blood clotting and has no definite nucleus, no DNA, and no hemoglobin.

Pleural effusion - also known as fluid in the chest, fluid on the lung or pleural fluid; a pleural effusion is an accumulation of fluid between the layers of tissue that line the lungs and chest cavity.

Pneumomediastinum - also known as mediastinal emphysema; air is present in the mediastinum.

Pneumonia - inflammation of one or both lungs; frequently but not always due to infection; the infection may be bacterial, viral, fungal or parasitic.

Pneumopericardium - the presence of gas in the pericardial sac.

Pneumoperitoneum - air or gas in the abdominal (peritoneal) cavity.

Pneumothorax - free air in the chest outside the lung.

Polycythaemia - an increase in the total cell mass of the blood.

Polydactyly - also known as hyperdactyly; a congenital physical anomaly consisting of extra fingers or toes

Polyhydramnios - excess amniotic fluid; can cause pre-term labor and is often an indication of fetal problems.

Potassium - the major positive ion (cation) found inside of cells.

PPHN - persistent pulmonary hypertension of the newborn; occurs when a newborn's circulation system does not adapt to breathing outside the womb.

Pre-eclampsia - also known as toxemia; A condition in pregnancy characterized by abrupt hypertension (a sharp rise in blood pressure), albuminuria (leakage of large amounts of the protein albumin into the urine) and edema (swelling) of the hands, feet, and face. Pre-eclampsia is the most common complication of pregnancy. It affects about 5% of pregnancies. It occurs in the third trimester (the last third) of pregnancy.

Priscoline - trademark for a peripheral vasodilator (tolazoline hydrochloride).

Prostacyclin - a prostaglandin produced in the walls of blood vessels that acts as a vasodilator and inhibits platelet aggregation.

Prostaglandin - any of a group of naturally occurring, chemically related fatty acids that stimulate contractility of the uterine and other smooth muscle and have the ability to lower blood pressure, regulate acid secretion of the stomach, regulate body temperature and platelet aggregation, and control inflammation and vascular permeability; they also affect the action of certain hormones.

Pseudomonas - an opportunistic bacteria that likes warm, moist environments; can survive in environments that other bacteria cannot; fairly common to see growing around an ET tube; resistant to many antibiotics.

Pulmonary hypoplasia - underdevelopment of the lungs; decreased lung volume.

Pulmonary vasospasm - see PPHN and/or PFC.

Pulse oximeter - a machine that reads the patient's heart rate and blood saturation levels through a probe attached to the patient's toe or finger.